The lone banana in the pic above is a Dwarf Orinoco that I transplanted there during the winter to provide some size perspective and to see if it would survive. It was already yellowed and dormant when I moved it in, and it stayed that way until March or so, when it started growing again. In the meantime I grew greens:
The coldest it ever got at ground level was 36F (outside temps were around 0F), which was great since it was entirely unheated. Next winter I'm hoping to keep the minimum temp around 45F by adding several thousand gallons of water (in tanks) to catch and radiate warmth. [EDIT: The 'next winter' of 2013/14 has now come and gone. I added small wading pools, about 800 gallons in total, which were helpful: even though this winter got about 10 degrees colder than last winter (-10F this winter, 0F last winter), the lowest it got at ground level in the greenhouse was around 39F. For winter 2014/15 I intend to scale up to several thousand gallons of water (as I had originally hoped to do last winter), and given my results with adding just 800 gallons, I think a minimum temp of 45F is within reach.]
As it became too hot for growing greens in the tunnel in early spring, I started moving some bananas in:
Then in early May I added some more:
Here they are at the end of May (left side, front to back, goes Raja Puri, Gros Michel, Double, Williams Hybrid, Dwarf Orinoco, Dwarf Cavendish; right side, front to back, goes Grand Nain, Kluay Khai, Dwarf Namwah, Misi Luki, Dwarf Brazilian, SH-3640):
6/13/2013
6/21
7/20
And then came the fruit!
